1. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 Analysis of a C4.1 flare occurred in a δ spot S.L. Guglielmino 1, F. Zuccarello 1, P. Romano 2, A. Cristaldi 3,4, M. Falco 1, I. Ermolli 4, S. Criscuoli 5 1 Dipartimento di Fisica e Astronomia – Università di Catania, Italy 2 INAF – Osservatorio Astrofisico di Catania, Italy 3 Dipartimento di Fisica – Università Roma Tor Vergata, Italy 4 INAF – Osservatorio Astronomico di Roma, Italy 5 NSO – National Solar Observatory, Sunspot, USA

2. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 Delta spot characteristics  Delta spot: a sunspot with umbrae of opposite polarities inside the same penumbra  Photospheric properties:  Strong shear flows are often observed along the PIL of flaring δ spots (Denker & Wang, 1998).  Curved penumbral filaments, cospatial to these shear flows and almost tangential to the sunspot umbra, can be observed in δ spots.  Such tangential penumbral filaments provide a first indication of highly twisted (sheared) magnetic field lines. 2 Many of the strongest and most geo-effective flares occur in δ spots!!! Cristaldi et al. (2014), ApJ 789, A162 Many of the strongest and most geo-effective flares occur in δ spots!!! Cristaldi et al. (2014), ApJ 789, A162

3. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 Observational data sets – NOAA 11267 InstrumentsWavelength Spectral points Pixel size (arcsec) Time resolution (sec) Observation days SST Fe I 5576 Å200.0592286 - 19 Aug 2011 Fe I pair 6302 Å15+150.0589286 - 19 Aug 2011 Ca II H core and WB-0.033896 - 19 Aug 2011 SDO hmi.M magnetograms-0.57205 - 7 Aug 2011 hmi.IC continuum-0.57205 -7 Aug 2011 hmi.V_Doppler velocities-0.57206 Aug 2011 aia.intensity-0.6126 Aug 2011 Observed on the 6 th of August, 2011 37 minutes of SST observations, starting at 09:00:05 UT 3 Ancillary data sets: XRT, Rhessi, Goes

4. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 - At the time of the observations AR NOAA 11267 was 2-days old - Classified as βγδ - 5 C-class flares during its passage across the solar disk HMI/SDO: Magnetograms and continuum images SST FoVSDO subFoVSDO Doppler velocities subFoV 4

5. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 HMI/SDO: Magnetic flux trend in NOAA 11267  The green band indicates the CRISP observing period  The vertical lines indicate the flares and their magnitude  During the time of CRISP observations the negative magnetic flux (blue symbols) is in a decreasing phase  The positive flux is almost constant (red symbols) The analyzed time interval corresponds to HMI magnetograms acquired from 00:00:00 UT on 5 August to 23:59:00 UT on 7 August. 5

6. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 - red contours: umbra - yellow contours: penumbra - red arrow: δ spot During the 21 hours reported in this sequence the δ spot changes its shape: the positive umbra decreases, while the the negative fragment persists and rotates in the clockwise direction 6 HMI/SDO: Evolution of AR NOAA 11267

7. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 Characterization of the plasma properties of the δ spot observed during the post-flare phase High Resolution Observations + SDO 7

8. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 Velocity fields in δ spots Earlier LOS velocity measurements of the region of separation between opposite polarities in δ spots (δ spot PIL) gave indication of upward motions. More recently: Martinez Pillet et al., 1994  Lites et al., 2002;  Denker et al., 2007; Prasad Choudhary & Deng, 2012 Takizawa et al., 2012  Supersonic downflows (14 km/s) and lower upflows of 1.5 km/s were detected along the δ spot PIL for about 3 hours Downflows and upflows (3 km/s) along the PIL: origin in the Evershed flow due to fluted penumbral filaments with opposing flows in interleaved magnetic field lines: abrupt bending of the penumbral filaments in proximity of the PIL Motions due to the submergence of an Ω-loop 8

9. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 HMI/SDO Dopplergrams Black arrow: location of the PIL separating the two opposite polarities of the delta spot. The LOS motions in the proximity of the δ spot PIL lasted for almost 15 hours !! 9

10. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 Indication of the location of upward (- 3 km/s) and downward (+ 3 km/s) motions along the δ spot PIL in the chromospheric image (inverted colors) Part of SST FoV selected for SIR inversion FoV of the figures displayed in the right panel FoV of the zoomed region CRISP/SST Data analysis 10 Chromospheric brightenings: ribbons during the post-flare phase… Here is the δ spot !!!

11. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 CRISP/SST: velocity fields along the δ spot PIL B C A  Velocity map obtained from the Gaussian fit of the Fe I 557.6 nm line  Strong evidence of upflows and downflows along the PIL separating the two magnetic polarities of the δ spot  The temporal behavior of the velocity in squares (9 x 9 pixels) A and B are reported in the plot  The trend reported indicates persistent upflows and downflows in the regions analyzed  The velocity measured in squares A and B can reach up to +/- 3 km/s 11

12. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 Map of the horizontal velocity field deduced using the LCT on Ca II H wide band images convergence in the region between opposite polarities Local Correlation Tracking (LCT) 12

13. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 Maps from SIR inversion of CRISP data - zoom 13

14. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015  The region between the two magnetic polarities of the δ shows its filamentary structure: a collection of highly sheared penumbral filaments  In the low chromosphere, we observe the evolution of the ribbons … SST: Ca II H WB and line core at 396.8 nm 14

15. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 Analysis of the C4.1 flare observed in the δ spot SDO + XRT + Rhessi + High Resolution Observations 15

16. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 Delta spot & flares  The complex configuration of δ spots magnetic fields often gives rise to a number of flares and eruptive phenomena, due to rearrangement of the magnetic field lines by reconnection  We identify such events in AR NOAA 11267  The yellow band indicates the CRISP observing period  The vertical lines indicate the flares and the eruptive phenomena  orange lines: flares  green line: CME  blue lines: ERU and LEA events 16

17. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 HMI/SDO: Magnetic flux trend in NOAA 11267  Again, vertical lines indicate the flares and the eruptive phenomena  The C4.1 flare occurs during a flux decay 17

18. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 HMI/SDO: Helicity flux trend in NOAA 11267  Most of the flares occur during the increasing phase of the helicity flux (LOS measurements) 18

19. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 The C4.1 flare in AR NOAA 11267  The strongest flare observed during the lifetime of the AR  Timing begin 08:37 UT peak 08:47 UT end08:51 UT  XRT activated the Target-of-Opportunity mode  SST began observations at 09:00 UT  Rhessi was in night at the peak, began observations at 08:59 UT  The flare occurred during the first decrease phase of negative flux of the δ spot and during helicity accumulation 19

20. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 SST: Ca II H line core post-flare ribbons 20

21. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 AIA/SDO: the C4.1 flare in NOAA 11267  Isophotes suggest that the C4.1 flare takes place in the δ spot PIL 21

22. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 AIA/SDO: the C4.1 flare in NOAA 11267 22 red contours: Rhessi 3-6 keV green contours: Rhessi 6-12 keV blue contours: AIA 335 isophotes

23. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 AIA/SDO: light curves 23 Starting time 08:00 UT

24. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 XRT/Hinode: evolution 24 FoV encompassing NOAA 11267 FoV encompassing control boxes (quiet regions) Starting time 08:00 UT

25. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 XRT/Hinode: light curves 25 T_decay XRT Be thick = 8.73 sec T_decay Goes 0.5 – 4 Å = 8.06 sec / Goes 1 – 8 Å = 4.47 sec Starting time 08:40 UT

26. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 Conclusions (i)  Observations of persistent downflows and upflows (3 km/s) observed with CRISP (40 minutes) and HMI (15 hours) in proximity of the δ spot PIL  The magnetic field is highly sheared along the δ spot PIL  The region shows a filamentary structure resembling a bunch of penumbral filaments wrapped around the negative polarity  The most probable process is related to penumbral filaments bending and diving in the subphotospheric layers, not to Ω-loop submergence . The observed motions may be therefore related to the Evershed flow in the bending field lines + - 26

27. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 Conclusions (ii)  AIA observations of the flares occurring in δ spot indicate that:  the flare occurs near the PIL  there are three ribbons and a Y-shaped structure  the light curves reach saturation…  Rhessi measurements suggest that the bulk of the X-ray emission is located near the crossing point of the Y-shaped structure  The emission in the XRT hardest filter has a trend comparable with that of Goes in the 0.5 – 4 Å channel. 27

28. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 Future work  Determine with full SDO spectropolarimetric measure- ments the helicity flux in this region  Compare more in detail the photospheric characteristics of the flare (HMI) with the chromospheric/coronal structures (AIA)  Study in detail the Ca II H SST dataset during the post-flare phase  Determine if the C4.1 flare occurred in NOAA 11267 is related with a CME observed after about 1.5 hour 28

29. S.L. Guglielmino eHeroes Final Meeting Leuven – 8 th February 2015 NOAA 11267 (6 August 2011) S17E24 Here is the δ spot !! Observational data sets – NOAA 11267 29